Soviets give two cheers for Libya;

The Soviets have staged a strained celebration of their marriage of convenience with Libya but are seen as much more concerned over relations with Washington, developments in Poland, and the crisis in Lebanon.

The just-completed Moscow visit by mercurial Libyan leader Muammar Qaddafi marked a propaganda gain for both sides -- with the Libyans getting strong support for their recent military intervention in Chad, and the Soviets getting (hedged) endorsement of their policy in Afghanistan.

Soviet President Leonid Brezhnev's main formal address during the Qaddafi visit, at a dinner April 27, focused less on Libya than on his troubled relations with the Reagan administration.

There is also unabated concern over Poland, as Soviet press coverage and private official remarks emphasize, although Moscow is reacting with initial caution to latest developments there.

And there is Lebanon, for six years the Arab world's smoldering fire, which is threatening more and more to engulf Soviet-allied Syria and US-allied Israel.

On April 28, Israel escalated its involvement in the latest fighting with an air attack on two Syrian helicopters only a few miles from the Syrian-Lebanese frontier. Syria, reports from the area say, has responded by setting up a battery of Soviet-manufactured surface-to-air missiles.

Earlier in April diplomats here had reported indications that the Soviets might see the Lebanese crisis as one means of activating their bid to reenter Arab-Israeli diplomacy, a province the Americans had quite happily monopolized in recent years.

But as the fighting has become more serious, Soviet news media coverage of the crisis has become slightly more restrained.

Arab and Western diplomats see this as a reflection of Soviet reluctance to risk a full-scale Arab-Israeli war, with dangers of superpower brinkmanship.

"I get the strong feeling that the Soviets are very much aware of the enormous danger of the Lebanese situation," a Western diplomat commented privately.

Colonel Qaddafi, during his Moscow visit, called for an "immediate rebuff" to Israel's "barbarous actions" in Lebanon. But the joint Soviet-Libyan communique was worded more softly, calling for an "immediate end" to outside aggression.

Still, at this writing, it remained unclear whether the Soviets had acted on an April 29 call from Washington to exercise restraining influence on the Syrians, a message reportedly also communicated during the Lebanese crisis by US diplomatic channels in Moscow.

The Soviets feel the fighting has been provoked, ultimately, by the US-armed Israelis in a bid to strike at the Soviet-backed Syrians and Palestinians in Lebanon.

A generally reliable Syrian source here said privately April 30 that the Soviets had not been urging restraint through officials in the Syrian embassy. But other diplomats pointed out such a message might well be conveyed in Damascus rather than here.

On the Polish front, the official Soviet news media reserved immediate comment on a crucial April 29 meeting of the Communist Party leadership in Warsaw.

The authoritative Soviet newspaper Pravda April 30 printed a lengthy transcript of remarks Polish leader Stanislaw Kania made at the meeting. Moscow Radio highlighted Mr. Kania's reported pledge to "preserve and strengthen" socialism, as well as remarks critical of the Solidarity trade union movement.

The Warsaw meeting set a date for an extraordinary Polish Communist congress widely expected to cement profound political reforms. The announcement was reported without comment by Pravda.

But the Polish Communist session did not sack prominent hard-liners, as Warsaw analysts had predicted at one time, presumably in part because of a surprise April 23 visit there by the Soviet Politburo's chief communist ideologue.

Two senior officials, speaking privately to this reporter shortly before the Warsaw meeting began, said they still viewed the Polish situation as serious.

But one suggested that Moscow, whose public statements have ruled out no policy alternatives in dealing with the crisis, had not yet come to any final assessment.

While criticizing the West for "salting the wound" in Poland, he said he thought the present situation was "steady, in relative terms. . . . It could get worse, or it could get better."